usr/src/lib/libc/port/fp/_base_sup.c

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21
  22 /*
  23  * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
  24  * Use is subject to license terms.
  25  */
  26
  27 #pragma ident   "%Z%%M% %I%     %E% SMI"
  28
  29 #include "lint.h"
  30 #include <sys/types.h>
  31 #include "base_conversion.h"
  32 #include <sys/isa_defs.h>
  33
  34 /*
  35  * Miscellaneous support routines used in base conversion
  36  */
  37
  38 static const union {
  39         unsigned int    u[2];
  40         double          d;
  41 } C[] = {
  42 #ifdef _LITTLE_ENDIAN
  43         { 0x00000000u, 0x00100000u },
  44         { 0x00000001u, 0x7ff00000u }
  45 #else
  46         { 0x00100000u, 0x00000000u },
  47         { 0x7ff00000u, 0x00000001u }
  48 #endif
  49 };
  50
  51 #define minnormal       C[0].d
  52 #define signalingnan    C[1].d
  53
  54 /* raise the floating point exceptions indicated by ef */
  55 void
  56 __base_conversion_set_exception(fp_exception_field_type ef)
  57 {
  58         double  t;
  59         volatile double tstored;
  60
  61         if (ef == (1 << fp_inexact)) {
  62                 t = 9.999999962747097015E-1;
  63                 /*
  64                  * 28 sig bits so product isn't inexact in extended
  65                  * accumulator, causing two inexact traps.
  66                  */
  67         } else if ((ef & (1 << fp_invalid)) != 0) {
  68                 t = signalingnan;
  69         } else if ((ef & (1 << fp_overflow)) != 0) {
  70                 t = 4.149515553422842866E+180;
  71                 /*
  72                  * 28 sig bits so product isn't inexact in extended
  73                  * accumulator, causing inexact trap prior to overflow trap
  74                  * on store.
  75                  */
  76         } else if ((ef & (1 << fp_underflow)) != 0) {
  77                 t = minnormal;
  78         } else
  79                 return;
  80
  81         /* Storage forces exception */
  82         tstored = t * t;
  83 }
  84
  85 /*
  86  * The following routine is no longer used in libc, but we have
  87  * to leave it for now because it's still used by Sun's old Fortran
  88  * runtime libraries.  Today this is a bug; in the days of SunOS 4.x,
  89  * when the relevant design decisions were made, it was a feature.
  90  */
  91 enum fp_class_type
  92 __class_quadruple(quadruple *x)
  93 {
  94         quadruple_equivalence kluge;
  95
  96         kluge.x = *x;
  97         if (kluge.f.msw.exponent == 0) {        /* 0 or sub */
  98                 if ((kluge.f.msw.significand == 0) &&
  99                     (kluge.f.significand2 == 0) &&
 100                     (kluge.f.significand3 == 0) &&
 101                     (kluge.f.significand4 == 0))
 102                         return (fp_zero);
 103                 else
 104                         return (fp_subnormal);
 105         } else if (kluge.f.msw.exponent == 0x7fff) {    /* inf or nan */
 106                 if ((kluge.f.msw.significand == 0) &&
 107                     (kluge.f.significand2 == 0) &&
 108                     (kluge.f.significand3 == 0) &&
 109                     (kluge.f.significand4 == 0))
 110                         return (fp_infinity);
 111                 else if ((kluge.f.msw.significand & 0xffff) >=
 112                     (unsigned int)0x8000)
 113                         return (fp_quiet);
 114                 else
 115                         return (fp_signaling);
 116         } else
 117                 return (fp_normal);
 118 }